package com.azhuo.utils.common;

import java.util.Map;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.jsp.JspException;
import javax.servlet.jsp.JspWriter;
import javax.servlet.jsp.PageContext;
import javax.servlet.jsp.tagext.TagSupport;

import com.azhuo.utils.Page;

/**
 * 分页导航
 * 显示格式
 * @author azhuo
 *
 */
public class NavigationTag extends TagSupport {
	private static final long serialVersionUID = 2372405317744358833L;

	/**
	 * 分页跳转的URL地址，此属性为必需
	 */
	private String url;

	/**
	 * request中用于保存Page<E>对象的变量名，默认为page
	 */
	private String bean = "page";

	/**
	 * 显示页码的数量
	 */
	private int number = 5;

	@Override
	public int doStartTag() throws JspException {

		JspWriter writer = pageContext.getOut();
		HttpServletRequest request = (HttpServletRequest) pageContext.getRequest();

		Page page = (Page) request.getAttribute(bean);
		if (page == null) {
			return SKIP_BODY;
		}

		url = resolveUrl(url, pageContext);

		try {
			// 得到总页数
			int pageCount = page.getTotal() / page.getSize();
			if (page.getTotal() % page.getSize() > 0) {
				pageCount++;
			}
			writer.print("<nav><url class='pagination'>");

			// 首页链接路径
			String homeUrl = append(url, "page", 1);

			// 尾页链接路径
			String backUrl = append(url, "page", pageCount);

			// 显示“首页、上一页”按钮
			if (page.getPage() > 1) {
				String preUrl = append(url, "page", page.getPage() - 1);
				preUrl = append(preUrl, "rows", page.getSize());
				writer.print("<li><a href='" + homeUrl + "'>首页</a></li>");
				writer.print("<li><a href='" + preUrl + "'>上一页</a></li>");
			} else {
				writer.print("<li class='disabled'><a href='#'>首页</a></li>");
				writer.print("<li class='disabled'><a href='#'>上一页</a></li>");
			}

			/*
			 * 显示当前页的前两页、后两页
			 * 若1，则：1 2 3 4 5
			 * 若2，则：1 2 3 4 5
			 * 若3，则：1 2 3 4 5
			 * 若4，则：2 3 4 5 6
			 * int indexPage = (page.getPage() - 2 > 0) ? page.getPage() - 2 : 1;
			 */
			int indexPage = 1;
			if (page.getPage() - 2 <= 0) {
				indexPage = 1;
			} else if (pageCount - page.getPage() <= 2) {
				indexPage = pageCount - 4;
			} else {
				indexPage = page.getPage() - 2;
			}

			for (int i = 1; i <= number && i <= pageCount; indexPage++, i++) {
				// 当前页
				if (indexPage == page.getPage()) {
					writer.print("<li class='active'><a href='#'>" + indexPage
							+ "<span class='sr-only'>(current)</span></a></li>");
					continue;
				}

				// 前、后两页
				String pageUrl = append(url, "page", indexPage);
				pageUrl = append(pageUrl, "rows", page.getSize());
				writer.print("<li><a href='" + pageUrl + "'>" + indexPage + "</a></li>");
			}

			// 显示“尾页、下一页”按钮
			if (page.getPage() < pageCount) {
				String nextUrl = append(url, "page", page.getPage() + 1);
				nextUrl = append(nextUrl, "rows", page.getSize());
				writer.print("<li><a href='" + nextUrl + "'>下一页</a></li>");
				writer.print("<li><a href='" + backUrl + "'>尾页</a></li>");
			} else {
				writer.print("<li class='disabled'><a href='#'>下一页</a></li>");
				writer.print("<li class='disabled'><a href='#'>尾页</a></li>");
			}

			writer.print("</nav>");
		} catch (Exception e) {
			System.out.println("自定义标签输出异常。。。");
			e.printStackTrace();
		}

		return SKIP_BODY;
	}

	private String append(String url, String key, int value) {
		return append(url, key, String.valueOf(value));
	}

	/**
	 * 为url添加参数对
	 */
	private String append(String url, String key, String value) {
		if (url == null || url.trim().length() == 0) {
			return "";
		}

		if (url.indexOf("?") == -1) {
			url = url + "?" + key + "=" + value;
		} else {
			if (url.endsWith("?")) {
				url = url + key + "=" + value;
			} else {
				url = url + "&amp;" + key + "=" + value;
			}
		}
		return url;
	}

	/**
	 * 为url添加翻页请求参数
	 */
	private String resolveUrl(String url, PageContext pageContext) {
		Map params = pageContext.getRequest().getParameterMap();
		for (Object key : params.keySet()) {
			if ("page".equals(key) || "rows".equals(key)) {
				continue;
			}

			Object value = params.get(key);
			if (value == null) {
				continue;
			}
			if (value.getClass().isArray()) {
				url = append(url, key.toString(), ((String[]) value)[0]);
			} else if (value instanceof String) {
				url = append(url, key.toString(), value.toString());
			}
		}
		return url;
	}

	public String getUrl() {
		return url;
	}

	public void setUrl(String url) {
		this.url = url;
	}

	public String getBean() {
		return bean;
	}

	public void setBean(String bean) {
		this.bean = bean;
	}

	public int getNumber() {
		return number;
	}

	public void setNumber(int number) {
		this.number = number;
	}

}
